(CNN) -- Police have released more than 60 soccer fans detained Saturday in downtown Moscow riots that injured 29 people, an interior department spokesman said Sunday, according to state-run media.

Hundreds of soccer fans clashed with Moscow police as an unsanctioned nationalist-tinged mass memorial for a fellow supporter turned violent, according to state media.

The confrontations took place in Manezh Square, outside the Kremlin, and led to the arrests of 65 Spartak Moscow fans for "disobedience," Moscow police spokesman Viktor Biryukov said, according to official Russian news agency Itar-Tass.

An undetermined number of people -- including several police -- were hurt in the clashes, news agencies reported.

Russian football has been in the spotlight since the country was named as the host of the 2018 World Cup finals earlier this month.

The head of the Spartak Moscow fan club told the semi-official news agency RIA Novosti that the showdown had nothing to do with sports but instead was rooted in problems in Russian society. Nationalist group members stirred the clashes, Russian Football Union president Sergei Fursenko told the news agency.

Some 5,000 fans of the Moscow soccer club had gathered to remember a fellow fan, Yegor Sviridov, who was killed December 6 in northern Moscow by several men from Russia's Caucasus region.

Police blocked their rally, but fans then started a fight with men from Caucasus, reported Itar-Tass. Hundreds of fans chanted nationalist slogans, with some throwing flares and smoke pellets at police.

Still, according to Itar-Tass, about 300 supporters "crushed everything" on their way from the square to the subway, breaking lights on escalators and smashing windows on a train.

Kolokoltsev said that he was confident that all those involved in the December 6 confrontation in northern Moscow would be arrested. Itar-Tass reported Friday that two of those suspects had already been detained.